The eventual goal of the current research is to develop probes for in vivo imaging of gene expression and for in vivo targeting of cells for killing or remediation. The current proposal describes a novel nucleic acid probe design that will provide the basis of the new technology required for these applications. These probes are also expected to be a major improvement over current probes for applications such as the analysis of bacterial and other contamination of foods and in the analysis of specific gene expression in cell and tissue samples. We call these "Targeted Revealed Aptamer Probes" (TRAPS). The basic innovation in the proposed TRAP design is the inclusion of an attenuated aptamer that is revealed on hybridization with a target nucleic acid. In the current proposal, the following specific aims are proposed: * Produce a basic TRAP probe. Determine that the TRAP probe only binds its ligand when the probe is hybridized with complementary RNA. Test for proportionality between the amounts of complementary RNA and ligand binding to the probe. Test for specificity of the interaction between the TRAP and the target RNA. * Produce a capture TRAP probe that can be used in capture assays and test its efficacy. PROPOSED COMMERCIAL APPLICATIONS: Initially, these probes are expected to be a major improvement on the current nucleic acid probes used for detection of DNA and RNA sequences such as in the analysis of bacterial and other contamination of foods and in the analysis of specific gene expression in cell and tissue samples. After further development, the probes will be used for in vivo imaging of gene expression and for targeting cells in vivo so that they can be killed or remediated.